Piezo-phototronic nanowire LEDs can scan your fingerprint, and then display it back to you

Share This article

By leveraging a new type of LED technology, called piezo-phototronics, researchers at the Georgia Institute of Technology have created a high-resolution nanowire array that has a truly astonishing number of potential uses, ranging from fingerprint readers to touch-sensitive robot skin to e-paper that allows you to sign your own personalized signature. In the future, this might be the perfect technology to implement a fingerprint reader in Apple’s iPhone 8.

It might seem slightly counterintuitive to have a single material that is both touch sensitive and light emitting, but that’s just one of the many wonders of nanowires. Basically, Zhong Lin Wang and fellow researchers at Georgia Tech have grown a forest of zinc oxide (ZnO) nanowires on a substrate of gallium nitride (GaN). The nanowires are grown via lithographic etching and low-temperature hydrothermal growth (basically the slow deposition of zinc oxide crystals from an aqueous solution). A transparent layer of indium-tin-oxide (ITO) is deposited on top, to complete the circuit and allow light to escape.

When pressure is applied to the nanowires, piezoelectricity is generated, which stimulates the production of photons at the root of the nanowire — where the n-type ZnO meets the p-type GaN. The harder you press, the stronger the current, the brighter the light. This variable sensitivity is what makes it ideal for use as synthetic e-skin, as well as tasks that are usually performed with conventional imaging, such as fingerprint reading.

What makes piezo-phototronic nanowires so intriguing is that they function as both an input and an output device — and an incredibly high-resolution input/output device at that. These LED nanowires have a spatial resolution of just 2.7 micrometers (micron), resulting in a pixel density of 6,350 DPI (about the same or better than the resolution of your DSLR’s CMOS sensor). If you poke the nanowires with your finger, the ridges and whorls on the end of your finger apply different amounts of pressure, causing the LEDs to produce an accurate image of your fingerprint. Likewise, you can imagine a sensor that can simultaneously capture your signature and display it afterward.

Moving forward, Wang believes the resolution of the device can be improved yet further by reducing the diameter of the nanowires, and by changing to a high-temperature process. At this point, it sounds like the applications for the piezo-phototronic sensor are mostly theoretical, and that the researchers still need to test whether it can actually be used as a fingerprint sensor, or glorified touch-sensitive e-paper. Importantly, the researchers say that the technology can be integrated with existing on-chip photonics solutions, such as those found in fiber-optic networking gear. As always with these incredibly new technologies, we’ll just have to wait and see where it ends up.

Research paper: doi:10.1038/nphoton.2013.191 – “High-resolution electroluminescent imaging of pressure distribution using a piezoelectric nanowire LED array”

Tagged In

Post a Comment

Techutante

“ranging… to touch-sensitive robot skin…” That sounds way cooler than slightly better touch-screens.

disqus_1dgobThMQc

Zhong Lin Wang…….LOL.

zapper

Wow , resolution better than DSLR CMOS sensor, great. So it can also be used as the DSLR’s sensor for image capture as well as the screen both, now you will be able to see exactly how the image looks in high detail (instead of grainy LCD image in cameras) in cameras as well as in smartphones. In other words smartphone screen can act as image sensor as well , exciting.

Yes, we have only begone to gather pebbles from the beach of knowledge. The ocean next to it remains unexplored.

http://slrman.wordpress.com/ James Smith

Yes, we have only begone to gather pebbles from the beach of knowledge. The ocean next to it remains unexplored.

Grant

I wonder whether it would be possible to incorporate nanodots that absorb light onto the material, so instead of producing light when pressure is applied to the substrate, they deform when the nanodots absorb light, creating a light activated artificial muscle.

Could make an awesome robot, a layer of artificial skin that detects tiny amounts of pressure applied to it, creating light, that could be sent to a photonic chip for processing, the photonic chip on processing could then send a light signal down to a layer of light activated muscle, causing it to deform dependant on how much light is sent.

If the piezoelectric deformed fast enough, it could make for quick robots, but would be awesome to have a completely photonic robot, feeling, thinking and reacting all based on light. Just need a power source that produces light (fusion????).

Use of this site is governed by our Terms of Use and Privacy Policy. Copyright 1996-2015 Ziff Davis, LLC.PCMag Digital Group All Rights Reserved. ExtremeTech is a registered trademark of Ziff Davis, LLC. Reproduction in whole or in part in any form or medium without express written permission of Ziff Davis, LLC. is prohibited.